My Obsession
by JindyUsagiShindou
Summary: Dipper and Robbie are closer than ever before, and everyone has started to see. But Mabel decides to get herself involved with getting them together. Muffin Explosion.
1. Chapter 1

Mabel was obsessed.

She didn't know how this had happened, but her room was cluttered.

With slash fanart.

It started out with that boy band Sev'ral Times. She thought two guys on there would be perfect together. Over time, she started pairing up boys more and more, until eventually the space under her bed was stuffed with fanart and fanfictions.

It was even worse now. Just yesterday she began to ship her brother and his "worst enemy" (or previously worst enemy). And she realized how AMAZING they would be as a couple. It made perfect sense, really. Dipper had just gotten over that futile crush on Wendy. And Robbie was around the Mystery Shack more than ever, certainly not to flirt with Wendy, because she was taking one of her "breaks" on the roof. Robbie would go in the living room.

And watch TV.

On the couch.

RIGHT where Dipper was.

They would talk and playfully "argue" about things. To Mabel, it seemed as if they were flirting. Sometimes, Robbie would play a song for Dipper. The song was usually something that involved screaming, but even though Dipper hated this kind of music, he listened anyway.

When Mabel questioned Dipper about this, he denied it, and swore they 'hated eachother' last year. Now they were 'sort-of-kind-of' friends. Still, Mabel had to wonder why her brother was STILL WEARING the shirt Robbie gave him at the teen's band's concert 3 days ago. Mabel didn't actually go to the concert, but Dipper talked about it nonstop for a day. That was enough to make her REALLY glad she missed it.

"So there I was, in the front row of Robbie's concert. And he signed this t-shirt and gave it to me- oh, and there was this one song I maybe liked-" he rambled on, his eyes shimmering with delight.

Wendy could verify this, of course, because she was the stage manager, and one of the only 3 people at the concert. The third person wasn't even there for the show, it was just a nearby old person complaining about the noise. Since Wendy was manager, she could recall all of the conversation at Robbie's house after they were finished.

* * *

_"Hey, Robbie, your biggest fan was here again tonight," the drummer snickered, pulling out a soda from the minifridge. Giggling followed from the rest of the band. Robbie rolled his eyes and sat down on the worn couch, leaning back into the faded blue cushions._

_"He's not my 'biggest fan'" he said, knowing they were referring to none other than Dipper Pines. "Anyways, we hate eachother. He probably just showed up to tease me about my music."_

_"You sure about that?" the other guitarist laughed. "The kid's more like a puppy dog. Following you around, waiting for your approval, wanting to lick you if he got the chance-"_

_"Shut up!" Robbie yelled. "Don't talk bad about Dipper, alright?"_

_"Ohhh, somebody's defensive!" the keyboard player singsonged. _

_"Wouldn't want anybody to hurt your BOYFRIEND!" the drummer mocked him, twirling her hair and batting her eyelashes jokingly._

_Robbie crossed his arms, annoyed at his bandmates. What was so hard about understanding he and Dipper were... well, actually, he didn't really know himself. The younger teen was kind of a pest, a cute pest... Ok not so much a pest..._

_Whatever. He didn't want to admit any of that stuff._

_"Guys, leave him alone," Wendy stepped in. "They're just kinda close-"_

_"Oh, they're WAY more than 'kinda close'. Why, just the other day, I saw them at them at the movies. Robbie's arm was around Dipper, and Dipper was falling asleep-"_

_"How would you even know this?" Robbie interrogated her. "Are you some kind of stalker?"_

_The drummer laughed, "It was a PUBLIC MOVIE THEATER. Besides, I was working the theater playing the animated movie you guys went to."_

_"Shows what you know. It wasn't an animated movie, it was a romantic drama!"_

_When he realized what he had confessed, his face turned red from embarrassment. Even WENDY was snickering now._

_"Not that we were... actually on a date or anything..."_

* * *

Wendy hesitantly told the story to Mabel for the seventh time. Mabel, listening intently, and making sure she got every detail correct, documented everything into a purple sparkly notebook that had the words "Operation Muffin" written on it in Sharpie. "Operation Muffin" is what she had nicknamed the task of getting Dipper and Robbie to be officially boyfriends, named after none other than their first words to eachother.

So far, Mabel had collected enough evidence to fill over half the book, but they STILL weren't together. She pondered over this for a while until coming to the perfect conclusion.

They were too proud to admit they liked eachother. They just needed that little push- and abracadabra- they would be making out in no time!

Hopefully Mabel would be the push they needed. Only, a little part of herself told her that maybe she should let them fall in love naturally.

But she would probably go CRAZY before that happened.

**So I wrote about three chapters of this story while I was gone... it was a lot of fun to write! **

**Please read and review! I love your feedback on my stories :)**


	2. Chapter 2

"Mabel... Mabel... MABEL!" a voice yelled, shaking her awake.

"Ah.. what?" Mabel woke, startled to see Wendy glaring at her. "What happened"

Wendy looked at her watch. "It's 12 PM, Mabel. You passed out at around 6."

Mabel immediately grabbed her notebook which had fallen off her lap and onto the floor. She groggily stood up, clinging to Wendy's arm for balance. "Why was I up so late?"

"Well, you drank about 10 bottles of soda, and kept saying something about your brother and Robbie. Anyways, it was pretty embarrassing when you stormed in here when we were watching the movie and told us they were kissing..."

"They were kissing?!"

"How should I know? You said it, not me," Wendy huffed. "They were both gone that night. You left for a few hours before that, and you were babbling about how you followed them and saw them kissing."

Mabel perked up. She had seen them kissing. This was HUGE news. Hopefully she had documented it in her notebook...

She frantically flipped through the worn pages until she spotted the paragraph she must have written last night. Attached was a picture she took outside of Robbie's house. There were two figures on the blue couch Wendy described either that resembled Dipper and Robbie. And they were DEFINITELY kissing. Filled with glee, Mabel attempted to decode her sloppy handwriting from last night.

"1:46 AM

OMG OMG OMFG I SAW DEM MAEKING OUT! LAST NITE DIPPUR SAID HE WUZ GOIN 2 A FREINDZ HOUSE SO I FOLLUWED HIM AND DERE AND IT TURNZ OUT IT WUZ ROBBIEZ HOUSE AND HE STAEYED TEH NITE! IT WULD HAEV BEEN PURFECT 4 ME BUT SUMETIHNG HAPUNED IT WUZ-"

The rest was unreadable, or written in a foreign language. She must have been sugar high; her English wasn't THAT bad.

Mabel was confused. Did something bad occur? Did they find out she was watching her? Where WAS Dipper? He hadn't been at the house this morning. Had she scared him off?

Even though this was most likely the case, Mabel asked Wendy if she knew anything. Wendy put down her "Teen" magazine and stared up at the overexcited 13-year-old.

"Last night he told us he was going to a sleepover, and that was all I had heard 'till you stormed in." she answered.

Mabel knew the only option.

Find her brother and stalk his love life.

She grabbed her pink flowery bicycle from the porch outside and started pedaling. Robbie's house wasn't too far. It was kind of an older house, with faded paint and bad screen doors and a squeaky floor. Apparently, his parents lived there with him, but they never seemed to be around. Robbie didn't like to talk about it. What he DID like to talk about was how he was going to get his own apartment. Which he paid for with the money he earned from his band, of course.

When she got to Robbie's house. Mabel bolted up to the door and knocked on it three times. When there was no answer, she kept knocking. Finally, someone answered the door.

It was Dipper. His brown hair was messy, looking as if he just woke up. He probably WASN'T fully awake yet.

And then she saw something.

Dipper was wearing ROBBIE'S HOODIE.

She felt giddy just staring at it. It was totally canon.

"Mabel, what are you DOING here?" he yawned, slightly surprised to see her here.

Her jaw was all the way to the floor. "Dipper, have you noticed what you're wearing?"

"Yes, Mabel, I know," he told her, annoyed.

"Is it for the reason I think it is?"

"What reason is that?" he inquired, being the innocent one of the twins.

"Nothing." She knew very well Dipper would never tell her something like THAT.

"You still haven't answered my question." Dipper stated.

"I came here to wonder why you didn't come home," she crossed her arms, eyeing him suspiciously. Though judging from the tousled hair and the hoodie and his boxers (at least she HOPED he had something covering him- the hoodie was oversized), she could pretty much assume the reason why he wasn't sleeping in their room that night. "Speaking of which, what were you doing last night?"

He was silent for a moment. "We just talked and stuff."

She didn't buy it. "Can I come in?"

"I don't know..." he trailed off, hearing footsteps coming down the stairs.

"Hey Dipper, who's at the door?" Robbie asked, approaching the door. He stood directly next to Dipper- no surprise there. He had on a black metal band t-shirt on and gray boxer shorts. He looked at Mabel hovering by the doorway. "Oh, hi, you need something?"

"She wanted to come inside," Dipper said, glancing up at Robbie for approval.

"Alright, sure, come in," he shrugged. He plopped down on the couch and started strumming his guitar.

"Do you want a soda, sis?" Dipper smiled, walking over to the minifridge. "Robbie has this new soda... I think it's called Sul... anyways, it's like a plum flavored soda.."

"Well aren't you a good waifu," she muttered, taking the drink he offered and cracking open the can. She had picked up a LOT of vocabulary from her stashes of BL manga, which she bought after she got into shipping.

The soda actually tasted nice for such a weird flavor. So Dipper had a hospitable side. Why wasn't he like this when her friends were over?

Oh yeah, he's with his boyfriend now.

Mabel stopped her train of thought to ask some more questions on her mind. "So... what were you two doing last night?"

Both of them looked up, thinking maybe she had figured it out. "Mabel, didn't I already tell you?" Dipper stammered.

"Not really. I don't buy it. It's not what I saw."

"What was that?" Robbie inquired. "Saw?"

"Oh, nothing." That was a close one. To save face in the awkward midst of the house, Mabel reverted back to her questions. "When are you coming back?"

Robbie was confused. "You didn't tell her Dipper?"

"I was GOING to." Dipper led Mabel into the kitchen. "Look Mabel, I'm going to be staying at Robbie's for a while."

Mabel was shocked. She knew Dipper would always, always, always want to spend time with Robbie. The entire Mystery Shack had picked up that idea months ago. But this was weird, even for Gravity Falls standards. "For how long?"

"I don't know how long," he rubbed his head nervously. "Robbie needs me right now."

"Dipper, don't play dumb with me," Mabel countered him. "I KNOW you two were kissing."

He blushed, stumbling back a bit. "Wha-What the hell are you talking about?"

"Oh Robbie!" she mimicked him. "I love you, and everybody knows it! Kiss me more! But let's keep this a secret from Mabel because it's not like she's MY SISTER OR ANYTHING!"

"Stop it!" Dipper yelled, his face completely red. "I don't have to tell you everything! You won't tell me what you're writing in that dumb notebook of yours!"

He was right. She didn't tell him that. But she always told HIM about a boy SHE liked. Why can't he do the same?

They argued about this for a little bit, until Robbie started playing so loudly the twins couldn't hear eachother anymore.

"That's his way of telling us to shut up," Dipper explained.

"No, it's his way of telling ME to shut up." Mabel griped, leaning on the counter. Dipper must have cleaned the kitchen before she came here, because the counter wasn't stacked with paper plates. "He loves you. He wouldn't wanna hurt you."

They stood in silence for a few minutes, the sounds of the old kitchen clock filling the room. Dipper and Mabel avoided looking at eachother.

Finally, Dipper sighed. "Mabel, I'm sorry, but I am staying here for now."

A pang of sadness hit her. Her twin brother wouldn't be there at the shack for a while.

On the other hand, they're living together now.

She could say that.

It sounds like they were dating.

Mabel grinned. "Hey bro, I'm sorry."

Dipper returned her expression. "It's ok. And... you meant it when you said you know Robbie loves me."

Mabel laughed a little on the inside. It was way too obvious now. "Of course I meant it."

So after their short-lived fight, there wasn't much to talk about. Mabel decided she could probably head home now."

"Bye!" she waved at her brother, getting on her bike.

"Bye, Mabel."

"Oh, and by the way, Dipper..." she started, smiling from ear to ear.

"What is it?"

"If you don't want me to think there's something 'special' going on between you two, it's probably best not to wear matching boxer shorts."

Dipper blushed. "M-Mabel!"

It was too late. She sped away on her bicycle, laughing.

When she arrived back at the shack, she noticed something peculiar.

Her notebook was missing.

**Yes. Quick update. You're welcome.**

**I may or may not have changed some things from my original draft, so forgive the mistakes.**

**Are you liking it so far? If so, please read and review!**


	3. Chapter 3

Mabel was spinning around in circles trying to find her notebook. She had checked under everything in the Mystery Shack, including Wendy, who was not too happy about the search.

Why had she even taken it with her in the first place? It was probably lost on the trail, or worse, Robbie or Dipper was lost IN it.

Oh, yeah. She remembered her obsession with them making out. That's most likely why she brought the glittery notebook along. Would this now be a detective story? Because that was Dipper's job, not hers.

Avoiding the unnecessary plot twist, Mabel got right back on her bike and retraced her steps. Or, tracks. Whatever.

So Mabel rode. And rode. Noting that it took much longer than the time before. Because of her ravenous hunger that randomly overcame her.

Since it was about 3-ish right now, she assumed the 'lovebirds' would be in town anyway. Dipper liked to eat early so he could save room for a midnight snack while doing his "detective work".

In town, the first thing she saw was Lazy Susan's diner, practically the only restaurant in town. She didn't want to go back to the place that creep Gideon took her to, so this place was fine. Sure enough, Dipper and Robbie were sitting at the bar stools, eating pancakes, "arguing" like they usually do. Using her quick instincts (or easily distracted mind. Whichever you prefer), she hid under a vacant booth.

"Kissssssssss," she whispered. They turned around to glare at her. "Nailed it!" she proclaimed.

"Mabel, did you follow us here?" Dipper rolled his eyes, clinging to Robbie's arm for some reason.

"Maybe, maybe not." She squinted her eyes. "I happen to know my notebook is missing."

"We dropped it off at the Mystery Shack," Robbie answered. "You left it at our house."

"And then we were starving, so we went out to eat," Dipper smiled, cuddling into the older teen's hoodie.

_OUR house? CUDDLING? _This was too much fanservice for Mabel to handle.

Mabel remembered the notebook. They had it all along? Well, so ends THAT plot device. Still, Mabel was curious to how they did not know they were CLEARLY DATING!

"You guys have been really close these past few months," she pointed out.

She probably shouldn't say anything more. After all, she had the perfect opportunity to observe them on their date!

"Could I eat with you guys?" Mabel asked them.

They looked at eachother, mulling over if they should really let this slightly insane girl eat with them. She would be recording every detail, every second of eye contact, and every brush of their hands.

Robbie sighed. "I've got nothing to lose. Sure, sit down"

Mabel smiled and sat down on the diner bar stool, resting her elbows on the table and cupping her soft hands on her face. Lazy Susan trotted over. "Can I get you anything, honey?" she politely asked.

"Just a soda. With a curly straw, if you have one." Mabel answered her. She glanced up at the ceiling for a minute before another session of not-obvious-at-all staring at Robbie and Dipper.

They were almost afraid to take another bite of their pancakes. Or _blink. _

"Erm... is something wrong?" Dipper nervously questioned, holding his fork in midair.

"No, no, carry on with your date," she let out a huge grim and began breathing heavily.

Silence flooded the restaurant. Everyone in the room focused their eyes and the three. It became extremely awkward for Robbie and Dipper, especially since Mabel hadn't blinked in over a couple minutes now.

The diner returned to normal only when Lazy Susan had delivered Mabel's soda to her.

"Oh, thanks." Mabel said, not really remembering that she had ordered it.

"You know, it seems pretty early for you guys to be eating dinner," she casually sipped her drink.

"Well, yeah, I get hungry late at night and eat a snack when I'm doing detective work," Dipper explained.

"Dipper, inspecting Robbie's pants does NOT count as detective work."

Robbie nearly choked on his drink. Dipper turned bright red. "MABEL," he whispered harshly.

"So exactly what kind of snack are we talking about here?..." She thought a bit about it and giggled to herself.

"Not whatever YOU'RE thinking, you pervert!"

"It's _true_," Mabel smirked.

Throughout the meal, she counted 12 hand-brushes, 5 games of footsie, and 7 minutes of eye contact in total. She hoped she would remember to write it down in the notebook.

Her plan was just beginning.

* * *

**Back with another chapter. So, even though I have a LOT of homework now, I can still sometimes find time to write during class, and I'm almost finished with the entire thing! **

**Please Read and review!**


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